Preheat your oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish with cooking spray or oil.

Heat a large skillet over medium-high heat. Add the ground beef and cook until browned, breaking it apart with a wooden spoon. This takes about 6-8 minutes. Drain excess fat if necessary.

Add the diced onion to the skillet and cook for 3-4 minutes until softened. Then, stir in the minced garlic and cook for another minute until fragrant.

Add the black beans, corn, diced tomatoes with green chilies, tomato sauce, chili powder, cumin, paprika, salt, and pepper. Stir everything together and let it simmer for 5 minutes. The mixture should be thick and flavorful.

Start layering your Mexican Casserole by spreading a thin layer of the meat mixture on the bottom of your prepared baking dish. Next, arrange a layer of tortillas over the sauce, tearing them as needed to cover the surface completely.

Spread half of the remaining meat mixture over the tortillas, then sprinkle with one-third of the shredded cheese. Repeat with another layer of tortillas, the rest of the meat mixture, and another third of the cheese.

Finish with a final layer of tortillas and top with the remaining cheese. Cover the dish with aluminum foil.

Bake the Mexican Casserole covered for 25 minutes. Then, remove the foil and bake for an additional 10-15 minutes until the cheese is bubbly and golden.

Let the casserole rest for 5-10 minutes before serving. This allows the layers to set and makes slicing easier.